This seems to have started happening within the past month, and it's a little annoying during development.
, and the jQueryUI_... resources have declared deps on jQuery. But they are included before jquery in the html.
Usually after one or more cycles of killing Cassini, cleaning the solution, rebuilding, and launching via Ctrl+F5 again, the problem goes away for a while. We mentioned this during this week's orchard weekly meeting and at least one or two other people mentioned they too were having this problem.